Notes on computational linguistics.pdf - UCLA Department of ...

Stabler - Lx 185/209 2003
(14) With this parsing strategy, we can avoid all blind alleys in collecting a tree.
/* ckypCollect.pl
* E Stabler, Feb 2000
* collect a tree from a CKY parser chart
*/
:- op(1200,xfx,:˜). % this is our object language "if"
ckypCollect(Chart,N,S,S/STs) :- collectTree(Chart,0,S,N,S/STs).
collectTree(Chart,I,A,J,A/ATs) :- member(((I,J):(A:˜L)),Chart), collectTrees(L,Chart,I,J,ATs).
collectTree(Chart,I,W,J,W/[]) :- member(((I,J):(W:˜[])),Chart).
collectTrees([],_,I,I,[]).
collectTrees([A],Chart,I,J,[A/ATs]) :- collectTree(Chart,I,A,J,A/ATs).
collectTrees([A,K|As],Chart,I,J,[A/ATs|Ts]) :- collectTree(Chart,I,A,K,A/ATs), collectTrees(As,Chart,K,J,Ts).
(15) We have sessions like this:
7 ?- [g1,ckypSWI,pp_tree].
% g1 compiled 0.00 sec, 672 bytes
% chart compiled 0.00 sec, 0 bytes
% agenda compiled 0.00 sec, 0 bytes
% items compiled 0.00 sec, 0 bytes
% monitor compiled 0.01 sec, 0 bytes
% driver compiled 0.00 sec, 0 bytes
% utilities compiled 0.00 sec, 0 bytes
% closure-swi compiled 0.01 sec, 0 bytes
% ckypSWI compiled 0.01 sec, 0 bytes
% pp_tree compiled 0.00 sec, 1,692 bytes
Yes
8 ?- computeClosure([the,idea,will,suffice]).
’.’’.’’.’’.’:’.’:’.’:’.’:’.’::’.’::’.’:’.’:’.’:’.’:’.’:’.’::’.’:
(0, 1): (d0:˜[the]).
(0, 1): (the:˜[]).
(0, 2): (d1:˜[d0, 1, np]).
(0, 2): (dp:˜[d1]).
(0, 4): (ip:˜[dp, 2, i1]).
(1, 2): (idea:˜[]).
(1, 2): (n0:˜[idea]).
(1, 2): (n1:˜[n0]).
(1, 2): (np:˜[n1]).
(2, 3): (i0:˜[will]).
(2, 3): (will:˜[]).
(2, 4): (i1:˜[i0, 3, vp]).
(3, 4): (suffice:˜[]).
(3, 4): (v0:˜[suffice]).
(3, 4): (v1:˜[v0]).
(3, 4): (vp:˜[v1]).
Yes
9 ?- [ckypCollect].
% ckypCollect compiled 0.00 sec, 1,764 bytes
Yes
10 ?- computeClosure([the,idea,will,suffice],Chart),nl,ckypCollect(Chart,4,ip,T),pp_tree(T).
’.’’.’’.’’.’:’.’:’.’:’.’:’.’::’.’::’.’:’.’:’.’:’.’:’.’:’.’::’.’:
ip /[
dp /[
d1 /[
d0 /[
the /[]],
np /[
n1 /[
n0 /[
idea /[]]]]]],
i1 /[
i0 /[
will /[]],
vp /[
v1 /[
v0 /[
suffice /[]]]]]]
Chart = [ (0, 1): (d0:˜[the]), (0, 1): (the:˜[]), (0, 2): (d1:˜[d0, 1, np]), (0, 2): (dp:˜[d1]), (0, 4): (ip:˜[dp, 2|...]), (1, 2): (idea:˜[]), (1, 2): (n0:˜[...]), (...
T = ip/[dp/[d1/[d0/[the/[]], np/[... /...]]], i1/[i0/[will/[]], vp/[v1/[...]]]]
Yes
11 ?-
Exercise: What grammar is the intersection of g1.pl and the finite state language with just one string,
{the idea will suffice}.
112